Operating frequency based power level altering in extended range wireless power transmitters

Abstract

A power transmitter for wireless power transfer includes a control and communications unit configured to provide power control signals to control a power level of a power signal configured for transmission to a power receiver and including a pulse width modulation (PWM) signal generator for determining and selecting the operating frequency from the operating frequency range. The power transmitter further includes an inverter circuit configured to receive a direct current (DC) power and convert the input power to a power signal, coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face, and a shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil.

The invention claimed is: 
     
       1. A power transmitter for wireless power transfer at an operating frequency selected from an operating frequency range, the power transmitter powered by an external power supply, the power transmitter comprising:
 a transmitter controller including a pulse width modulation (PWM) signal generator configured to determine and select the operating frequency from the operating frequency range, the transmitter controller configured to provide power control signals to the external power supply and control a power level of an alternating current (AC) power signal for transmission to a power receiver; 
 an inverter circuit configured to convert a direct current (DC) input power to the AC power signal; 
 a transmitter coil configured to transmit the AC power signal to the power receiver; and 
 wherein the external power supply is configured to generate the DC input power based on the power control signals and provide the DC input power to the inverter circuit, wherein the external power supply comprises:
 a voltage regulator, and 
 a power supply controller configured to:
 (i) receive the power control signals; 
 (ii) generate voltage regulation instructions for altering a DC voltage of the DC input power, wherein the voltage regulation instructions comprise one or more instructions to select the DC voltage of the DC input power, and wherein the DC voltage is selected from one or more preset DC voltage levels comprising a first DC voltage level that is electrically associated with a first AC power signal level and a second DC voltage level that is electrically associated with a second AC power signal level; and 
 (iii) provide the voltage regulation instructions to the voltage regulator to control the DC voltage of the DC input power, and 
 
 
 wherein a frequency shift is determined such that an alternating current (AC) output power level is greater than the first AC power signal level and less than the second AC power signal level. 
 
     
     
       2. The power transmitter of  claim 1 , wherein the operating frequency range is about 87 kilohertz (kHz) to about 205 kHz. 
     
     
       3. The power transmitter of  claim 1 , wherein the preset DC voltage levels include one or more of 5 Volts (V), 9 V, 15 V, or 20 V. 
     
     
       4. The power transmitter of  claim 1 , wherein the transmitter controller is further configured to
 receive power request signals from the power receiver, and 
 determine the power control signals based on the power request signals. 
 
     
     
       5. The power transmitter of  claim 1 , wherein the transmitter controller is configured to provide frequency shift signals to the PWM signal generator and alter the power level of the AC power signal by shifting the operating frequency selected from the operating frequency range. 
     
     
       6. The power transmitter of  claim 1 , wherein the AC output power level is in a range of about 10 milliwatts to about 60 Watts. 
     
     
       7. The power transmitter of  claim 1  further comprising a ferrite core comprising at least a top surface that defines a cavity, and wherein the transmitter coil comprises at least one layer of wound Litz wire and at least a top face, and wherein the transmitter coil is positioned within the cavity such that the ferrite core substantially surrounds all but the top face of the transmitter coil. 
     
     
       8. A base station for wireless power transfer at an operating frequency selectable from an operating frequency range, the base station comprising:
 a transmitter controller including a pulse width modulation (PWM) signal generator configured to determine and select the operating frequency from the operating frequency range, the transmitter controller configured to provide power control signals and control a power level of an alternating current (AC) power signal for transmission to a power receiver; 
 an inverter circuit configured to convert a direct current (DC) input power to the AC power signal; 
 a transmitter coil configured to transmit the AC power signal to the power receiver; 
 a power supply external to a power transmitter, wherein the power supply is operable to configure a DC input power based on the power control signals and provide the DC input power to the inverter circuit, wherein the power supply comprises:
 a voltage regulator, and 
 a power supply controller configured to:
 (i) receive the power control signals; 
 (ii) generate voltage regulation instructions for altering a DC voltage of the DC input power, wherein the voltage regulation instructions comprise one or more instructions to select the DC voltage of the DC input power, and wherein the DC voltage is selected from one or more preset DC voltage levels comprising a first DC voltage level that is electrically associated with a first AC power signal level and a second DC voltage level that is electrically associated with a second AC power signal level; and 
 (iii) provide the voltage regulation instructions to the voltage regulator to control the DC voltage of the DC input power, and 
 
 
 wherein a frequency shift is determined such that an alternating current (AC) output power level is greater than the first AC power signal level and less than the second AC power signal level. 
 
     
     
       9. The base station of  claim 8 , wherein the operating frequency range is about 87 kilohertz (kHz) to about 205 kHz. 
     
     
       10. The base station of  claim 8 , wherein the preset DC voltage levels include one or more of 5 Volts (V), 9 V, 15 V, or 20 V. 
     
     
       11. The base station of  claim 8 , wherein the AC output power level is in a range of about 10 milliwatts to about 60 Watts. 
     
     
       12. The base station of  claim 8 , wherein the transmitter coil comprises at least one layer of wound Litz wire and at least a top face. 
     
     
       13. The base station of  claim 12  further comprising a ferrite core comprising at least a top surface that defines a cavity, wherein the transmitter coil is positioned within the cavity such that the ferrite core substantially surrounds all but the top face of the transmitter coil. 
     
     
       14. The base station of  claim 12 , wherein the at least one layer comprises a first layer and a second layer, and wherein the first layer includes a first number of turns in a range of about 4 turns to about 5 turns, and wherein the second layer includes a second number of turns in a range of about 4 turns to about 5 turns. 
     
     
       15. A system for wireless power transfer at an operating frequency selectable from an operating frequency range, the system comprising:
 a power transmitter comprising:
 a transmitter controller including a pulse width modulation (PWM) signal generator configured to determine and select the operating frequency from the operating frequency range, the transmitter controller configured to provide power control signals to control a power level of an alternating current (AC) power signal for transmission to a power receiver; 
 an inverter circuit configured to convert a direct current (DC) input power to the AC power signal; 
 a transmitter coil configured to transmit the AC power signal to the power receiver; and 
 
 a power supply external to the power transmitter, wherein the power supply is operable to configure a DC input power based on the power control signals and provide the DC input power to the inverter circuit, wherein the power supply comprises:
 a voltage regulator, and 
 a power supply controller configured to:
 (i) receive the power control signals; 
 (ii) generate voltage regulation instructions for altering a DC voltage of the DC input power, wherein the voltage regulation instructions comprise one or more instructions to select the DC voltage of the DC input power, and wherein the DC voltage is selected from one or more preset DC voltage levels comprising a first DC voltage level that is electrically associated with a first AC power signal level and a second DC voltage level that is electrically associated with a second AC power signal level; and 
 (iii) provide the voltage regulation instructions to the voltage regulator to control the DC voltage of the DC input power, and 
 
 
 wherein a frequency shift is determined such that an alternating current (AC) output power level is greater than the first AC power signal level and less than the second AC power signal level. 
 
     
     
       16. The system of  claim 15 , wherein the operating frequency range is about 87 kilohertz (kHz) to about 205 kHz. 
     
     
       17. The system of  claim 15 , wherein the preset DC voltage levels include one or more of 5 Volts (V), 9 V, 15 V, or 20 V. 
     
     
       18. The system of  claim 15 , wherein the AC output power level is in a range of about 10 milliwatts to about 60 Watts. 
     
     
       19. The system of  claim 15 , wherein the transmitter controller is configured to generate frequency shift signals that are provided to the PWM signal generator and alter the power level of the AC power signal of the inverter circuit by shifting the operating frequency selected from the operating frequency range. 
     
     
       20. The system of  claim 15  further comprising a ferrite core comprising at least a top surface that defines a cavity, and wherein the transmitter coil comprises at least one layer of wound Litz wire and at least a top face, and wherein the transmitter coil is positioned within the cavity such that the ferrite core substantially surrounds all but the top face of the transmitter coil.